Ffice



UUflIllu Ull ll-nUllUl "fiNsYLvAmA.

Ram-mmmama. sla -s- 1 s m an iv I g 1,1883. J I i ADP nuke 5, cap-cameras I v V 1 To all whom concern; v inseparating the alloy of silver, zinc, andlead it known that -I, WIILIAM TATHMI,3- above referred to: The first mixture com 9 citizen of the United States, and a resident of prises, bestus: one part, by weight; raw fire- 5 Philadelphia, Pennsylvania, have invented clav. iour parts, by weight; old fireb11211;

' s'rncrr'rcnrrou forming p'irt oiYLett'ei-a Eaten No. 281,159 unteu July 10, 1883.

g certain Improvementsin Protecting Plumbago' round two parts, by weigh I; Crucibles, of which the following is a specifia e 0 SM; or potash-six parts, By weight. cation. 1 p o'jt 1s 1s a e a -e water to reduce the v v Q The object of my invention istoiprevfent the compound to the consistency oi mortar. The r rapid destruction of the plumbago retorts and second mixture comprises asbestus two parts, 1 crucib es used in various metallurgical operby w-ei ht lithar e. one pal y weightrawtions, and this object I attain in the manner firc-cla oil art, by weight; owdered lass,

hereinafter set forth. am y weight; old fir r10 grou I 3 What areknownas plumbago retorts'and' one part, by weight. e as esus, besides crucibles are made "of'a mixture of black lead aiding the composition to resist the destructive 15 (carbon in the form of graphite) and fire'clay efi'ects of the fire, servesas abinder to prevent in varying proportions, and are generally sub-' the fire-clay from cracking when subjected to s jected to high temperatures, as in melting steel heat, and before the vitrifiable ingredient of i or brass, or separating the alloy of zinc, silver, the compound becomes fused. I 3 f I t and leadobtained in the process of d'esilver- .The above compounds are simply given as eo ization'of lead by zinc. These crucibles are examples, and my invention is not limited rapidly destroyed,"owing to the burning out thereto. 1 of the plumbago or carbon, the fire-clay being ,When the crucible is tube subjected to avery j leit behind as a porous and more or less friable high temperature-'ssuchns ,thatemployed in mass, which readilycombines and forms a slag melting steel, for instance-I find it necessary 5 with the ashes or cinders fi'om coke or coal. to add a portion of aluminato the com- The burning out of the carbon is due to two pound for the following reason: ,The value of causes: first, the presence of oxygen or atmos- 'a fire-clay one compound having fire-clay'as a pheric air; and, SGCOD'df'thB presence of carbase, as regards its abilityto resist intense n i bonic acidthe productnf combustion in the heat, dependsiupon the relative proportions of l a 0 furnace. To obviate this difliculty, therefore, aluminaandsiiicacontained therein and upon 'l tpropose to provide each crucible with anem the proportionofotherbases,-suchassoda,iron,

tve'lope impervious to air dangers and capable potash, &c.,which fmay be called fluxes. of resisting the heat to which the "crucible is The more alumina in proportionfto silica con- "subjected. 1 t 1 tained in the clay or compound; the morere- 1 7 5 out my invention lrap ally to the fiactgry bathe same,-and, on thel other outside of the crucible a mixture whic on the hand;tlic:more' flux'contained in they clay or application of heat, will form a vitrified coat: -co'inpoundtheless'heatwill it The ing, which adheresifirmly to the retort and r addition ofasbestlisttfidwitrifiableingredients 0 j protects the latter fromthe destcriictive influ-J? fto fire-clay causegproportionsof alumina, silio encesdue-to theactu'on of air or or the ca, and flux linrfthe eompound "jvery difl 'erent v y heatedretort. Variouscompoundsmay-beused --from-those wvhich cizisted in the dire-claw") I. Q, forthe purpose,the following conditions being: hence vhen the'coinpoundisin ;ndedto resist I g j l observed: The compound must not be such ...veryhigh temperatures, I add to it "sufiicient 5 that itwill flow 011 the crucible when'melted... alumina to properly temper it-that isto say, t(j 4 'Jt'must'vitrifyomthefapplication of heat, and izocerrectthldBsof-refiactory quality, due:to it mustlbe ofgsuch a nature that it twillanotzbe ,thejcxcess of silica-and fluxes. The amount of p destroyed bi 'iieat, combineread} depend upon-the I "*ily with'the ashes or eindcfs'fi mLthe-iire :to' character of cla' "used upon'the proportions r00 fform slag. 1 of-rasbestusjsdl ble silicate, &c.,mixed there-v "Thei'ollowing are two whidh'Ihave with, and upmhich the compound oundto give good results in practice when is intended towithstand. The alumina may -subjectedtosuchtemperaturesasthosereached: be in'the form of the alumina hydrate of con1- time, or may the mineral known .fbauxiteflwhichisahydrateofaluminawith varying quantities of iron and silica and about twenty per cent. water. The bauxite used is the white variety, which is the purest, and is 7 preferably calcined.

vI am aware that asbestus has been added to clay in the manufacture of heat-resisting bricks, and also that it has been proposed to 'i 1o glaze crucibles to render them damp-proof, and

hence claim neither of these things; but

I claim as my invention 1. The within-described compound for forming a protecting-coating for crucibles, the same 15 comprising fire-c1a-y,asbestus, and an ingredient which will become vitrified on the appli cation of heat, as set forth. v

ing a protecting-coating for crucibles, the same comprising asbestus, soluble silicate, and fireclay, as specified.

"33. The within-described compound for forming a protecting-coating for crucibles, the same comprising fire-clay, asbestus, a vitrifiable ingredient, and alumina, as set forth.

s In testimony whereof I have signed my name to this specification in the presence of two subscribing witnesses.

WILLIAM TATHAM.

Witnesses:

HARRY L. ASHENFELTER, HARRY SMITH.

l The within-described compound for form- 

